Is there any way that diesel exhaust could back up the anti-siphon valve [which is part of the 1999 36MKII Aqualift Muffler exhaust system] and therefore, make it's way into the cabin? I have a diesel "exhaust" smell [not raw diesel] that has been plaguing us for years.
We have replaced the manifold gasket, sent the stainless steel exhaust manifold with insulation to Catalina who gave it a pressure test to make sure it was not cracked [it was OK], inspected and tightened all fittings involved in the exhaust system, am replacing the "hump hose" between the Aqualift muffler and the thru-hull valve this spring.
The only thing left could be the anti-siphon valve. Anyone ever have a problem with that -i.e. - exhaust leaking back in the cabin. I realize it is not a carbon-monnxide threat, but it's the "smell".
Any help would be appreciated from anyone.
Captain Mike
Captain Mike
I feel for you.
It appears you have given due diligence to your trouble shooting plan. It would be nice to know if the replacing of the "hump hose" between the Aqua lift Muffler and the thru- hull valve this spring have any effect.
A few questions. Does this diesel exhaust odor happen regardless of apparent wind direction or sea state? Do you have a full enclosure or not? Is the odor worse with the wind aft? Is it worse when the wind is up a bit.? Do you have the odor when there is no wind? Have you experimented at the dock or is it just an issue when you underway? Is the odor worse under higher revs or just lower revs.
The reason I ask these questions is that I have been through this with a friend who had a Tyana 42. It turned out that it was his full enclosure design, He had a canoe stern and it appeared that the exhaust through hull was located perfectly for issues under down wind conditions on a flat sea.
I have a full enclosure on my C-36 MKII and have never had the issue that you describe.
A few thoughts.
Mark
Mark Wey
Terrmar III #2179
Goderich Ont.
Mike,
Another source of smell could be the crankcase vent. I'm not sure when they changed it, but earlier Universals had a crankcase vent hose that vented the crankcase down into the engine compartment. It went straight down from the engine fitting and dissapeared below the engine. Later models fastened the vent hose to a spot near the air cleaner. As the engine sucks in air, the dirty air (sort of smelled like diesel, sort of smelled like oil) gets sucked in, too.
Also, I'm a little confused by your reference to the hump hose. The silicone rubber single hump hose is fastened between the SS exhaust riser (the part you had pressure tested at CY?) and the aqualift muffler. It has nothing to do with the thru hull valve. If there are any black streaks around the fittings at the aqualift muffler, you might have found the problem. The fiberglass tubes that extend out of the aqualift muffer are not always perfectly round and/or smooth. Even if you tighten the hose clamps on the heavy black exhaust hose, you may not be getting a good seal. Maybe inspect the tubes on the aqualift carefully for imperfections? The single hump hose might help, at least with one of those connections.
The anti-siphon valve is easy enough to take apart and inspect. Unscrew the black cap on the top of it. Inside of it is a very small rubber piece shaped like a duck bill. The duck bill part should be pointing downward, into the valve. If the duck bill is deformed, or clogged with salt or other junk, it will not function properly. You would see water squirting out of it when the engine is running. If it is dry when the engine is running, most likely it is working fine. The smaller hose that is connected to the anti-siphon loop carries cooling water, not exhaust gases, so I doubt it is the cause of your smells.
Tom Sokoloski
C36/375IA Past Commodore
Noank, CT